Tayside prisoners have been tormented by rats, wasps and ants in the last two years.
Figures provided by the Scottish Prison Service show that almost £4,000 was spent on dealing with pest control problems at HMP Perth.
HMP Castle Huntly saw £2,400 worth of call-outs during the same time period.
Concerns were repeatedly raised about rodents, with reports of mice droppings in parts of Perth Prison as well as sightings of vermin in the visitor centre and nightshift staff quarters.
The figures, released through a freedom of information request, also showed that £845 was spent at Perth on installing pigeon spiking on the building.
Bosses at Castle Huntly also approved £1,186 of rodent treatment between 2016 and this year.
Issues with mice in the visitor centre in Castle Huntly were also reported, along with treatment for wasps nests.